Crawler drive mechanism



4 Sheets-Sheet 1 INVENToRs 4 A'r oRNEY l l n Oct. 23, 19.45A. w. M. HUsToN Erm.l

CRAWLER DRIVE MEHANISM Filed Aug. 14, 1942 Oct- 23; .1945- y w. M.A HusToN ETAL 2,387,268

I l 'CRAWLER DRIVE MECHANISM I Filed Aug. 14,A 1942.- 4 sheets-sheet 2 Oct. Z3, 1945.

w. M. Husl'ToN Erm.

CRAWLER DRIVE MECHANISM Filed Aug. 14, 1942 4 Smets-'sheet s l "I v i I E i w h) w i L Q r Q 1 a S Q ifiV la A TORNEYS CRAWLER DRIVE MCHANISM '4 sheets-sheet 4 Filed Aug. 14:, 1942 Patented Oct. 23, 1945 CRAWLER DRIVE MECHANISM William M. Huston and Cecil E. J ones,

Lima, Ohio Application August 14, 1942, Serial No. 454,792

(ci. 18o-9.2)

11 Claims.

This invention relates to drive mechanism of the type employed on self-propelling machines such as power shovels, draglines, excavators and the like.

Ordinarily, 'a machine of this general type includes a truck having ground-contacting drive elements, such as crawler treads, at each side thereof, the truck serving to support a rotating base on which is mounted a power unit and various devices and machinery for effecting the op- L erations for which the machine is designed, such as hoisting, crowding, swiveling of the base, and

traveling of the machine on the crawler treads.

Most commonly, a machine of this character is steered by locking one or the other of the two treads and applying power to the tread not locked, thereby causing the machine to turn to one side or the other.

Broadly, the present invention contemplates an improved drive mechanism providing for diierential drive on the two treads, that is, for drive of the two treads at diierent rates, for steering purposes. This is of advantage since it reduces strains on various parts of the propelling mechanism, including the truck frame, the crawler According to the invention, control means are provided interrelating the operation of the several transmissions, the control providing for disconnection of the normal drive at one side when the third transmission is coupled at that side,

In the preferred construction, the third transmission has a ratio providing for a lower speed than the other two.

In connection with the above, it is to be noted that, in accordance with the invention, a total of only three transmissions or sets of gears is required to accomplish all of the propelling functions, including drive at both sides at the same rate and dierential drive as between the two sides, either side being capable of drive at a sion is made for electing the several' drive functions with a minimum of gears'and other parts. This is of further advantage in view of the fact that the available space in the crawler truck is relatively limited.

It is further noted' that the several 4shafts and gears required in 'the drive mechanism are arranged in a novel manner, especially from the standpoint of the bearings employed, theresult being an unusually compact and yet rugged construction, as will'appear hereinafter.

Still further, the invention contemplates a novel form of control incorporating a-uid pressure actuable device mounted on the' rotating base and a mechanical vactuating connection eX- tended from said device to controuable parts of the power transmission on the crawler truck. This fluid pressure device may be actuable either by air pressure or by hydraulic pressurasuch as oil pressure. The `mechanical connection is desirably arranged coaxially of the axisl on which the rotating base is mounted. Moreover, .the power for propelling the machine is carried from the prime mover o'n the rotating base to the'truck through a shaft also arranged coaxially with the axis of swiveling of the base. `By locating the fluid pressure deviceon the rotating bas'e' and employing a mechanical connection from thereto the truck, all pressure connections'maybe made much more readily accessible than where the pressure device is mounted on the truck. Servicing, for instance, for repairy of leaks, isthereby greatly simplified.

In addition to all ofthe above, the invention provides, in a machine of the ,Character'described a driving and steering mechanism characterized by compactness, adequate clearances between' and accessibility of parts, simplification of structure, minimization of rst cost, reduction of wear, and thus of maintenance and repair costs by reduction of the number of gears and other moving parts operating 'during propelling and/or steering, minimization of friction, thus saving engine power, improvement of the support for bearings, clutches and other partsjand an increase in ruggedness of the arrangement.

How the foregoing objects and advantages are attained will appear more-fully from the following description referring .to the accompanying drawings, which illustrate two forms of 'construction, and in which- Figure 1 is a transverse vertical sectional View of one form, illustratingportions of a ycrawler truck, and showing in elevation the outline of higher rate than the other. In this way, provi- 55 Athe rotating base mounted on the truck, together with drive parts arranged in accordance with the invention, this view being taken in the vertical plane indicated by the line I-l on Figure 2;

Figure 2 is a view illustrating drive mechanism in the truck, the view being taken from the bottom;

Figure 3 is a transverse sectional view taken in the vertical plane indicated by the line 3 3 on Figure YSi.: y

Figurer! is ,arfi'agmentary view of: cer-,tain details taken as indicated 'by'theline 4-4 on Figure 2; and

Figures 5 and 6 are views similar to Figures 2 and 4, illustrating a second formof. construction.

As indicated in Figures 1 and 3, themachine is adapted to rest on and travel'on the ground on a pair of crawler treads 5 5. The crawler truck 6 is associated with the treads and the ro.-V

tating base I is mounted on the truck by means of the center pin 8 about which the base may turn, 'litho base serves to support machinery, in.- chidinea prime mover, for the purpose of effect,

the operations for whichthe machine is designed.

Power is adapted to be delivered-to the :usual crawler: :tread .sprockets 1(not` shown), through drivemechanism now to be described. A vertical shaft. fextends through'the center pin mou-nt.- 'ing, the upperl end of .the shaft being provided with .oscar |10 adaptedtobecoupled to the prime mover on the rotating :hase in a manner well understood insthis art, the coupling ordinarily including a. controllable clutch.

At its lower end, the vertical shaft 9 carries a bevel gear il meshing with gear l2, which latter is keyed-on. the travel 1shaft I3 which extends transversely of and isjournaled inthe truck frame structure..

Right-hand and left-hand shafts I4 and I5 are also 'journaled in the truck framathese two shafts heing positioned in alignment with .each other, aszclearly appears in Figures 2 and 3, and beingsomewhat oiset from transverse sha-ft I3. Shafts I4 and AI5 are. providedi with splined sections2 I6 and' .Hon which are mounted the clutch devices. I8- and- I 9.

'Power is adapted to he transmittedfrom shaft I3 to shaft I4 through a pair of gears 2.0 and 2l, the former .of which is fixedon shaft I3 and the vlatter:oifwhich is freely. rotative on shaft I4. Geari2l, however,l is providedv with jaw clutch projections cooperating with complementary parts formed on clutch I8, so that upon inter.- engagement of these parts, shaft I4 is caused to rotate with gear 2l.

At the other side .of the machine a similarset of gears 22 and 23 is arranged, the .clutch I9 serving to connect. gear 23 with shaft I5..

The two shafts I4 and I5 are. provided with sprockets 24 and 25, each adapted to he .coupled by means of a. chain with the sprocket for the tread a-t that side of' the machine, in a manner understood inthis art.

The foregoing drive mechanism serves to tra-nsmit power fromfthe prime mover .on the rotating base to the two crawler treads, and since the sets of gears 2U-.2| and 22-43. are of the same ratio, this drive will actuate the two tread driving sprockets at the same rate, thereby effectin straight-.line travel of the machine.

In accordance with the present invention provision is made for an alternative condition of drive in which either one of the. tread sprockets is driven at a iower rate than :for normal straightline travel. For this. purpose, a third se'tof gears 26 and 2'I is employed, the gear 2S being keyed to transverse travel shaft I3 and gear 2'! being carried by a shaft 28 journaled in the truck frame intermediate the pair of shafts I4 and I5. As best seen in Figure 3, the adjacent ends of the three aligned shafts (I4, 28 and I5) are desirably journaled with reduced inner end portions Ma and I5a extended into the two ends of shaft 28, the` ends of shaft 28,'inY turn, being exteriorly iournazled .in thetruck framing. This provides a rugged 'and' yet compact bearing arrangement.

The two ends of shaft 28 are further provided with jaw clutch parts adapted to cooperate with .complementary parts formed on the clutch devices l and IH.. Thus, when clutch I8 is moved inwardly, gear '2l is disconnected from shaft I4.

and gear 2T is engaged and, on the other hand, when clutch I9 is moved inwardly, gear 23 is disengaged from shaft I5 and gear 21 is coupled therewith.

',Iilev foregoing mechanism, therefore, provides for positive drive .at the two sides 'of the nuetclfxine at diercrrt rates, so that the machine can be turned in one direction or the other. As above noted, .this is of advantage since. itreduees .strain on various of the driving pants, including the treadsthemselves, A.drive chains, :truck frame, etc., as compared, with an arrangement such vas commonly .employed in the prior art where Aturning is eifeeted by positively locking one or` the other of the treads.

According to the invention, thev control'for the `ciu-tchesY,I8. and I-S preferably. comprises a me ohahical connection from the truck tothe rotating .basent which point the mechanical connection is ydesirably actuated by a fluid pressure power device, Thus, in Figure i, a doub`le-acting fluid pressure piston and cylinder appears at 2B, being understood that suitable Afluid pressure supply lines (-fragmentarily shown) are associated with the cylinder, so asto introduce and exhaust pressure uid (for instance, air or oil), as vby means of any convenient .operatorscontrol valve, The cylinder is mountedby bracket 30 0.11 the rotating base and the piston is coupled with one arm 3i of a bell .crank pivoted at 32, the

other `arm 3.3 of this -beil crank being biiurcated.

,to embrace control rod 34. Ajoint 3-5 of known type Per-mits free relative rotation of arm 33 of the bell crankwith respect tol control rod 34, While ai; the Same time providing for transmission of up and'V .down control movements to said oontrol rod.

YThe control rod passes downwardly through the vertical drive shaft 9, thelower end being connected with an arm 36 which is fixed on shaft 3?, Upward and downward movement o f the .control -rod 34 thus causes the shaft3l to oscillate in its bearings indicated at `33 in Fig-ure 2.

As best seen in Figure- 4, shaft 37 has a squared end carrying another arm 39 which is connected with short arms 48 and 4I by .means of links 42 and 4'3, arms 49 and 4I being xed `Orishafts 54 and 45.. lShafts 4,4 and .45 are appropriately journaled in the` truck frame and carry bifurcatcd clutch shifter arms 46 and 41. Arms, 45 and 4f! -cooperate,v respectively, with clutchesi and I9, serving to eiect lsliding rum/'ementV of these .clutcheson their spline mountings i6 and I7.

.In considering the parts just mentioned, it may bc noted that since Figure 2 is a bottom View, the parts appear in inverted positions in Figure 4. Actually .control shafts 44Y and '45 lie above the -transmission'shafta as is shown in Figure 3, and

the shifter arms 46I and 41 extend downwardly to cooperate with the clutches. y

For the purpose of maintaining the two clutches in their outer positions (in which gear sets 2li-2! and 22-23 are in operation) a transverse rod 48extends between arms 40 and 4I being connected therewith by pins 48a and 4Ia. One end of rod 48 has a freely'sliding mounting in pin 48a and a compression spring 49 reacts against this pair and also against an abutment 50 carried by the rod 48. The opposite end of rod 48 is xed in pin 4Ia, both pins, however, being rotatively mounted in the arms to accommodate control movements. The net resultof the -spring is to urge the two arms 48 and 4I away from each other, and this normally maintains the clutches I8 and I3 in their outer positions, shown in Figures 2 and 3.

Before considering the operatiOn of the'control mechanism, it should further be noted that links 42 and 43 also have a sliding fit with arms 48 and 4I, although each link is providedwith an abutment at its outer end, such as indicated at 5| and 52, through which the associated arm may be pulled inwardly.

In the normal or mid-position of adjustment of the control, which is the position illustrated in the figures, spring 49, as aforesaid, maintains the two clutches in their outer positions, and in this condition the drive is at the same rate at the two sides of the machine, so that straightline travel is effected.

Upward or downward movement of the control rod 34, by actuating the fluid pressure device 29, causes one or the other of links 42 and 43 to operate the clutch at that side of the machine. For instance, assume downward movement of control rod 34. This will cause arm 38 on shaft 31 to rock to the right when viewed as in Figure 4. Abutinent 52 on link 43 now engages arm 4I and causes this arm to rock, also toward the right, thereby producing a similar movement of clutch shifter arm 41, so that clutch I9 is disengaged from gear 23 and engaged with gear 21. At the same time, the movement of link 42 at the other side of the mechanism merely results in a sliding of this link with respect to arm 4I), so that clutch I8 remains in its normal position in which gear 2I is coupled with shaft I4. The slipjoint at the right-hand end of rod 48 (as viewed in Figure 4) prevents this rod from interfering with the described movement of arm 4I. Compression spring 4'9, under the conditions described above, is merely slightly compressed and still remains operative to maintain clutch I8 in its position of engagement with gear 2|.

Similar action takes place upon upward movement of the control rod 34, although at this 'time clutch I8 is shifted to the left so as to disconnect gear 2I and connect gear 21 with shaft I4, clutch I9 remaining in engagement with gear 23.

From the foregoing it will be seen that the invention provides for drive at both sides of the machine at the same rate, or for employment of a different rate of drive at the two sides, the control being effected by the operator normally stationed in the cab on the rotating base.

The control system is of advantage from a number of standpoints, it being of especial importance that a mechanical actuating connection is utilized from the truck to the rotating base,

' and the pressure power operating means is mounted on the rotating base, being coupled with the mechanical connection at that point. This ment of clutch 56.

avoids lthe necessity for taking pressure connections through the center'pin mounting into the truck.

Various of the advantages above enumerated are.. also secured by the modified construction f illustrated in Figures 5 and 6.

In the form of Figures 5 and 6, the truck frame is indicated at 5a, the travel shaft I3a being journaled in the truck frame as in the form first described. Bevel gear I2a is adapted to mesh with a complementary gear mounted on the vertical shaft (not shown) through which power is transmitted from the power plant on the rotating base to the drive mechanism in the truck frame. Shaft 13a, in the form of Figures 5 and 6, 4is relatively short, but is arranged in alignment with additional shafts 53 and 54 carrying sprockets 24a and 25a adapted to cooperate with chains through which the driving power is transmitted to the tread sprockets.

Shaft 53 carries a clutch device 55, the clutch ,being splined to the shaft. A similar clutch device 53 is splined on shaft 54. In addition shafts 53 and 54 carry spur gears 51 and 58, respectively, which spur gears are freely rotatable on the shafts, but are adapted to be locked to the shafts through the clutches 55 and 5S, the pairs of gears and clutches having complementary clutch teeth as shown in Figure 5. The clutch devices 55 and 55 are further adapted to cooperate with clutch teeth formed on parts 58 land BIJ, the former being formed with gear 6I which is fixed on shaft I3a, and the latter being formed with gear I2a, which is also fixed .on shaft I3a.

When the two clutches (55 and 56) are both moved inwardly, 'shafts 53 and 54 are directly connected with shaft I3a, thereby transmitting power in the same ratio to the two sprockets 24a and 25a.

Drive of the tread at one side, or the other, at a lower rate is provided for by the mechanism described just below. Y 1

A supplemental shaft 62 arranged parallel to shafts ISG., 53 and 53 has fixed thereon a gear 63 meshing with gear 5I, and also a pair of gears 54 vand 65 meshing respectively with gears 51 and'58.

'When one of the clutches (for instance 55) is moved outwardly, the gear at that side (51) is connected with shaft 53, in view of which the drive at that side ofy the machine then takes place from shaft I 3a. through gears 6I and 63 to shaft 62, and from there through gears 64 and v5l' to shaft 53. Since gear 64 is smaller than gear 5'1, this series of drive connections provides for a lower rate'of drive than is provided by the direct coupling of shaft Ilia to shaft 53 through clutch 55. The tread at the other side may sim- Vilarly be driven at a lower rate by outward move- When clutches 55 and 56 are in the inner positions, gears 6I, 63, 64, 65, 51 and 58 merely idle. e The foregoing construction provides low-"loss transmission of power during straight-ahead propel (both treads driven at the'same rate), since this drive need not be carried through any pairs of gears in the truck frame.

The location of the several shafts and gears above described is also of importance since the arrangement is very compact and further since the disposition of the several parts makes possible better bearing supports for the sprockets 24a' and 25a. Still further, this arrangement isf vof advantage since more room is provided for the axles :and other parts between thepropel chains. These pointsare of especial importance for the reason that the available space in the truck-is relatively limited The control mechanism for operating clutches 55 and 5B issimilar to that described above in connection with'Figures 1 to 4 inclusive. However,` since the clutches operate in the opposite senses .from the arrangement of Figures 1 to 4, a slight, re-.arrangernent of control parts is reqnired, as will appear just below.

The main horizontal control shaft is adapted to he actuated from the rotating base inthe same manner as described above. 'I'his shaft (31m-carries an arml 65 coupled by. means of links 5.1 and .63 with arms 69 and 10, the latter lacing mounted on shafts 1l and 12 which are ilhiatelv journaled in the truck frame as before.. Shafts H and 'I2v again carry shifter arms 13 and 14 cooperatingrespectively with clutches 55 and 56.

Tensionspring 15 interconnects-pins 1B and 11 which are rotatively mounted on the short arms 63 and 1B. This tension spring normally urges the shifter arms toward each other and thus normally maintains the clutches 55 and '56 in their inner positions. When it is desired to move one of the clutches (55 or 56) outwardly, the control shaft 31a is actuated (from the manual control on the rotating base) so as to rock arm 66 toone side or the other, thereby moving one or the other of arms 69 and 10 outwardly. For this` purpose links 51 and 68 carry abutments 18 and 19. The end portions of links S1 and B8 are also slidable in apertures through pins 16 and 11, and toward the extremity of each link another abutment is provided (80 and 8|), this abutment being spaced so as to permit free movement ofthe arm 66 in either direction from its mid-position in order to move either of clutches 55 and 58 outwardly. These outer abutments (80 and 8|) will also serve to insure thatv one clutch or the other is always retained in its inner position.

With regard to both forms of construction .above described, it is particularly to be noted ond form, there is a further reduction in friction ,and wear, since the straight ahead propelling operation takes the drivingload oi of six of the spur gears. f

Other advantages of the invention will be obvious to those skilled inthe art, and it will also loeY apparent that various changes, alternatives,

omissions, and additions may be adopted, within the scope of the invention as disclosed and as defined' in the claims.

We claim: l. In a machine adapted to travel on a pair of crawler treads, said machine having a crawler truck, a rotating base mounted on said truck, and

a power unit carried by the rotating base, drive mechanism for said crawler treads including a vertical shaft driven by said power unit and eX- tended downwardly from the rotating base to the crawler truck, a transverse shaft mounted in the truckV and geared to said vertical shaft to be driven therefrom, right-hand and left-,hand shafts adapted respectively to` drive the rightand left-handV treads, the rightand left-hand shafts bein-g mounted in alignment with the transverse-shaft, `disconnectihle clutches for coupling the-right vand left-hand shafts with said transverse shaft'to provide for drive of the two treads at the same rate, and a disconnectible power transmission connected with the transverse shaft havingfa different drive ratio and being adapted toibo coupled with either of said right.- and left-hand shafts.

2. A construction in accordance with claim 1 in which the drive through said power transmission is at a lower rate than'through said clutches. 3.. A construction in accordance with claim 1 in which said power transmission includes a shaft offset from the first shafts and disconnectible gearing for selectively coupling said offset` shaft witheither of'said rightand left-hand shafts.

4.' A construction in accordance with claim .1 in which said power transmission includes a shaft offset from the first shaft and disconnectible gearing for selectively coupling said offset shaft with either of said -rightand left-hand shafts, said' gearing being in constant mesh but having disconnection lmeans arranged to relieve 'it of-thel driving load.

5. A construction in accordance with claim 1 and further including mean-s normally urging the disconnect-ible clutches toward positionsm which the rightand left-hand shafts are connected with the transverse shaft;

6. A construction in accordance with claim l and further including means normally urging the disconnectible clutches toward positions in which the rightand left-hand shafts are connected with the transverse shaft, and controllabe means for actuating the clutches providing for alternative disconnection of the ri'ghtand left-hand shafts from the transverse shaft and for connection of said disconnectible power transmission to that one ofthe rightand left-hand shafts which is disconnected from the transverse shaft.

7. A construction in accordance with claim l and 4further including controllable means for actuating the clutches and providing for alternative disconnection of the rightand left-hand shaftsl from the transverse shaft and for connection of said disconnectible power transmission to that one of the rightf and left-hand shafts which is disconnected from the transverse shaft.

8. A construction in accordance with claim l in which the tread drive through the disconnectible power transmission is at a lower rat-e than that provided by connection of the rightand left-hand shafts through the disconnectihle clutches, the construction further including controllable means for actuating the clutches providing for alternative disconnection of the rightand left-hand shafts from the transverse shaft and for connection of said disconnectible power transmission to that one of the rightand lefthand shafts which is disconnected from the transverse shaft.

9. A construction in accordance with claim 1 in which the said power transmission ,includes a shaft offset from the first shafts, a set of gears interconnecting the offset shaft and the transverse shaft, and independently controllable disconnectible sets of gears for respectively connecting the right-A and left-hand shafts with said offset shaft.

10. A construction in accordance with claim 1 in which the said power transmission includes a shaft oiiset from the rst shafts, a set of gears interconnecting the offset shaft and the transverse shaft, and independently controllable disconnectible sets of gears for respectively connecting the rightand left-hand shafts with said offset shaft, the disconnectible clutches being provided with means serving to effect connection and disconnection of said disconnectible sets of gears.

\ 11..A construction in accordance With claim 1 in which the said power transmission includes a shaft offset from the rst shafts, a set of gears interconnecting the oiset shaft and the transverse shaft, and independently controllable disconnectible sets of gears for respectively connect- WILLIAM M. HUSTON. CECIL E. JONES. 

